1. Field of the Invention
The present invention relates to an optical fiber end-surface polishing device having a ferrule fixing device, which is applicable to an optical fiber end-surface polishing device for simultaneously polishing a plurality of optical fibers.
More specifically, the present invention relates to an optical fiber end-surface polishing device having an improved ferrule fixing means that allows ferrules with optical fibers to be attached to and detached from a holder plate for polishing by a simple operation.
2. Description of the Related Art
The present inventor has made several inventions regarding an optical fiber end-surface polishing device for simultaneously polishing a plurality of optical fibers.
Among them are the following four inventions, all of which relate to a polishing device capable of simultaneously polishing the end surfaces of a plurality of optical fibers:
U.S. Pat. No. 4,831,784 "POLISHING APPARATUS FOR END SURFACES OF OPTICAL FIBERS" PA1 U.S. Pat. No. 4,979,334 "OPTICAL FIBER END SURFACE POLISHING DEVICE" PA1 U.S. Pat. No. 5,216,846 "METHOD AND APPARATUS FOR GRINDING FOREMOST END OF A FERRULE" PA1 Japanese Patent Laid-Open No. 6-179161 (U.S. Ser. No. 08/019,303) "APPARATUS FOR GRINDING END FACES 0F FERRULES TOGETHER WITH OPTICAL FIBERS EACH FIRMLY RECEIVED IN FERRULES" PA1 ferrule accommodating sockets provided in the holder plate and having through holes for receiving ferrules, the ferrule accommodating sockets imposing a limit to the descent of the ferrules; PA1 ferrule presser levers supported so as to be rotatable on stationary shafts substantially parallel to the through holes and biased downwardly by a biasing means, PA1 wherein each ferrule presser lever is movable between an angular position where the ferrules inserted into the associated ferrule accommodating sockets are pressed downwardly and an angular position where the polished ferrules can be detached.
These inventions relate to a polishing device in which the end surface of an optical fiber to be polished is pressed against a polishing disc while effecting a relative movement composed of turning and revolution, thereby polishing the end surface of the optical fiber.
FIG. 3 is a plan view of a polishing holder or holder plate in a conventional optical fiber end-surface polishing device for simultaneously polishing the end surfaces of a plurality of optical fibers; and FIG. 4 is a sectional view showing a ferrule fixed to the holder plate of the conventional polishing device shown in FIG. 3.
A holder plate 1 for polishing is formed as a disc and has at its center a cylindrical hub section 2 into which a holding shaft (not shown) is inserted.
Arranged along the circumference of a concentric circle, indicated by the dashed line E, are a plurality of mounting members 3 of the same structure for mounting devices with optical fibers. The sectional view of FIG. 4, taken along the line4--4 of FIG. 3, shows an example of the polishing holder for polishing. FIG. 4 shows an end surface 6 of an FC-type ferrule 5 to which an optical fiber 4 is attached.
Each mounting member 3 has an accommodating socket 7 for fixing the ferrule, and a cap nut 9. The socket 7 for fixing the ferrule has at its center a through hole for accommodating the FC-type ferrule 5 and is forced into a hole provided in the holder plate 1 and secured therein. Further, a male screw 8 is provided in the outer periphery of the socket 7 for fixing the ferrule. The cap nut 9 has a slit 10 and a female screw 8a to be engaged with the male screw 8 to fix the FC-type ferrule 5.
The operator tightens the cap nut 9 to fix the optical fiber ferrule 5 to the holder plate 1, and presses the end surface 6 of the ferrule 5 against the polishing disc 11 to perform polishing by a relative movement such that the tip end of the ferrule 5 with an optical fiber describes an arcuate trajectory.
In many conventional optical fiber end-surface polishing devices, the mounting of the ferrule 5 with an optical fiber is effected by inserting the ferrule 5 into the through hole of the ferrule accommodating socket 7 and then engaging the slitted cap nut 9 with the male screw 8 provided on the outer peripheral surface of the socket, as described above.
This structure has a problem in that the slitted cap nut 9 is liable to be lost during operation and that it takes 10 to 20 seconds per unit to effect fixation by tightening the nuts. Further, whereas the principal dimensions of the currently-used optical connector ferrules are: an outer diameter of 2.5 mm and an effective length of 8 mm, an optical connector ferrule whose dimensions are approximately reduced in half is being developed and will be put into practical use to reduce the size of optical circuit systems. In this regard, the conventional structure based on screwing as described above is expected to become too minute, making the mounting operation rather difficult.